IGF1 and breast cancer: To elucidate the effects of CR (with and without IGF-1 infusion) on mammary tumor progression, we injected MMTV-Wnt-1 mammary tumor cells in a separate cohort of C57BL/6 mice (n = 15 mice/group) that were randomized to receive the same control, 30% CR, and 30% CR + IGF-1 regimens described above.